Lifting-jack



O. K. M0INTI RE.

LIPTING JACK.

'Patented'May 13, 1884.

(No Model.)

l NITED STATES ATnNT Marien.

LIFTINGMJACK.

SPECIFICATION forming part of Letters Patent No. 298,700, dated May 13, 1884.

Application filed March 15, 1884. (No model.)

To @ZZ whom, it may concern:

Be it known that I, OLIVER K. MOINTIRE, a citizen ofthe United States, residing at Springfield, in the county of Clark and State of Ohio, have invented certain new and useful Improve ments in Lifting-Jacks; and I do declare the following to be a full, clear, and eXact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the letters and iigures of reference marked thereon, which form a part of this specification.

My invention relates to improvements in lifting-jacks.

My invention consists in the manner of pivoting the lever, and of pivoting the pawls to the lever, whereby the jack is rendered more easy of operation and the power required to operate the lever decreases toward the end of its movement. I accomplish this by pivoting the lower or greatest lifting-pawl at some distance above the horizontal plane of the ful- Crum-pin of the lever, thereby causing its pivoted end to be thrown outward toward a perpendicular drawn through the fulcrum-pin of the lever as the latter is forced downward.

Figure l is a vertical section through the jack standard or body, and shows the position of the operative parts. Fig. 2 is a perspective view of the head end of the lever, and shows the pawls pivoted thereto.

In the drawings, A is the lifting-j ack, which is constructed with the usual hollow standard, a, within which the toothed lifting-bar c slides loosely up or down, and which latter is operated by lever B and its two pawls, c and f, respectively. Pawl c is the main or lifting pawl, although the pawl f also lifts the bar a to a less extent when the lever B is raised above a horizontal line. The latter pawl is the stop or retaining pawl. Both of these pawls are pivoted in the same plane in the top surface of the lever, while the fulcrum-pin of the latter is near the lower edge ofthe same. Pawl cis in the form of a stout hook, with a short bend at the lowerend, and is suspended from lits journals d, which rest in recesses on either side of the slot k at the upper angle of the end of lever B. A small pin, d', extends axially through the journals d and head of the lever, to prevent the pawl c from being displaced. Lever Bis pivoted between lugs c', cast on the standard a, and has a wide and substantially square head with rounded angles; and pawl c is pivoted at the upper angle about one-half farther in distance from the fulcrum-pin b than the pawl f, so that when the lever B is thrown downward pawl c will lift bar a about twice the height that pawl f will when the lever is thrown upward, the difference being shown in the dotted lines on either side of the jack in Fig. l, the vertical lines representing the vertical movement of bar a when operated by each pawl. The line on the left indicates the movement of the bar a when lifted by pawl c as the lever B is thrown downward, and the vertical line on the right indicates the same movement of bar c when lifted by pawl f as the lever is thrown upward. In each movement the pivotal points of the pawls are thrown to the same perpendicular over the fulcrum b. The pivot of pawl c passing through the arc of a circle whose radius being about one-half greater than that of the pivot of pawlf, the lift of the former pawl is in the same increased proportion. Pawl o is provided with a knob, g, which answers both as a handleto detach the pawl from its engagement with the notches e in the bar a', and to serve as an additional weight to facilitate the engagement of its point e with the rack or notches of the bar a when the lever B is raised preparatory to the operation of the jack.

I claim as my improvementl. In a lifting-jack, the combination, with the lifting-bar and lever, of a lifting and a stop pawl, both pivoted in the saine plane of said lever above the fulcrum of the same, the lifting-pawl being suspended below said lever, and having its pivotal end thrown outward over the fulcrumof the latter when operated,

whereby the power necessary to operate in lifting is decreased toward the end of the throw of the lever, substantially as set forth.

2. In a lifting-jack, the combination, with the lever and lifting-bar, of a lifting and a stop pawl, both pivoted in the same plane above the fulcrum of said lever, the pivot of the lifting-pawl being about one-half greater distance from the fulcrum-pin than the pivot of the IOO stop-pztwl, whereby said lifting-pztwl is caused to lift twice the vertical height of the latter .in opera-ting the Same, as set forth. o

3. The combination and arrangement, with the lever and lifting-bar, of the two pawls pivoted in substantially the same plane of the lever, the lower or lifting pawl being pivoted at the upper angle of the end of said lever, suspended through a slot therein below the same, and -provided with a. weighted knob extending therefrom, to disengage it from the lifting-bar and to aid it by its gravity in engaging therewith, substantially as set forth.

v2Y 'y 298,700

4. In a. lifting-jack, the combination, with standard a, lifting-bar a', and vlever B, with slot lc, of pawls c and f, pivoted to the latter, as described, said pawl c being suspended below Said lever and provided with a weighted knob, and adapted to be operated substantially as set forth. v

' OLIVER K. MCINTIRE.

Attest-.Q

B. C. CONVERSE, W. M. RHODES. 

